Optus has blamed a software upgrade for last week’s outage, which left millions without phone connections and internet services.
The 12-hour outage left 10 million individuals and businesses high and dry last Wednesday, unable to make or receive calls, or complete transactions.
WATCH THE VIDEO ABOVE: Optus provides reason for crippling shutdown
Watch the latest News on Channel 7 or stream for free on 7plus >>
The cause has now been determined, the company said in a statement on Monday, and steps have been taken to ensure it won’t happen again.
“At around 4.05am Wednesday morning, the Optus network received changes to routing information from an international peering network following a routine software upgrade,” the company said.
“These routing information changes propagated through multiple layers in our network and exceeded preset safety levels on key routers which could not handle these.
“This resulted in those routers disconnecting from the Optus IP Core network to protect themselves.”
The time taken to restore the system was longer than anticipated as some of the routers needed to be physically rebooted, requiring Optus staff to be deployed across a number of sites across the country.
“The restoration of the network was at all times our priority and we subsequently established the cause working together with our partners,” the telco said.
“The restoration required a large-scale effort of the team and in some cases required Optus to reconnect or reboot routers physically, requiring the dispatch of people across a number of sites in Australia.
“This is why restoration was progressive over the afternoon.
“We have made changes to the network to address this issue so that it cannot occur again.”
Optus will co-operate with reviews launched by the government and the Senate.
Data compensation
Following the outage, Optus said customers will be entitled to extra data as compensation.
But critics of the network say it’s not enough and are demanding more.
Optus CEO Kelly Bayer Rosmarin on Thursday confirmed eligible postpaid customers will be able to access 200GB of extra data after the bungle, and have until the end of the year to activate it.
Eligible prepaid customers will also be able to access unlimited data on weekends until the end of the year.
Customers on eligible mobile SIM and mobile data SIM plans, including business customers, can add at least 200GB of extra data before the end of the year.
Starting from November 13, customers can add 100GB of data for each eligible service per payment cycle for three months through the My Optus app or by contacting Optus.
Customers on an eligible prepaid plan will receive free unlimited data, starting from November 18, every weekend until the end of the year.
